1. Field of the Art
This invention relates to an oligonucleotide derivative useful as a probe for hybridization. More specifically, the present invention relates to an oligonucleotide derivative having a plurality of labels introduced on the extension of the 5'-end or the 3'-end.
2. Prior Art
In recent years, with the remarkable developments in the technical field of genetic engineering, various techniques have been established and are being applied also to other fields. For example, the hybridization method [B. D. Hames and S. J. Higgins: Nucleic Acid Hybridization (IRL Press (1985))] is being applied to cloning of genes as a matter of course and also to fields of medicine, particularly diagnosis of gene disease.
On the other hand, we have developed oligonucleotide derivatives also usable for the above hybridization method and have already made proposals [Japanese Laid-Open Patent Publication No. 148798/1984 (hereinafter called prior invention .circle.1 ) and Japanese Laid-Open Patent Publication No. 204200/1984 (hereinafter called prior invention .circle.2 )].
The prior invention .circle.1 is an oligonucleotide derivative in which biotin is introduced on the extension of the 5'-end phosphate of nucleotide, while the prior invention .circle.2 is similarly an oligonucleotide derivative in which 2,4-dinitrophenyl (DNP) group is introduced. These derivatives had the following advantages as compared with the probe for hybridization of the prior art.
a. Since no biotin or DNP group is contained at the purine or pyrimidine base moiety of the nucleotide, no change occurs in the melting point (Tm value) and therefore it is stable.
b. Synthesis of biotin- or DNP-oligonucleotide having any base sequence is possible.
c. A short chain oligomer is sufficient as a probe.
d. Synthesis is very simple, and synthesis of a large amount is possible.
e. It can be also utilized as the primer (DNA fragment for reversetranscriptase or DNA polymerase).
Therefore, these can be used as a probe for hybridization or as a probe for diagnosis of gene disease.
However, when the above oligonucleotide derivative is applied for diagnosis of gene disease, its detection sensitivity has been a problem.